A Berlin ironwork necklace with cross pendant showing a tiny butterfly at its' centre, 19th century. Berlin maker's mark stamped verso, in 1813, Princess Marianne of Prussia appealed to her countrywomen to exchange their gold jewellery for a brooch or a ring of iron with the inscription 'Gold Gab Ich fur Eisen' (I gave gold for iron). This public effort supported the general appeal of Rudolph Werkmeister published in Berlin on March 31, 1813, a call for funds in response to the Napoleonic campaigns. The entreaty elicited a huge response. 'Eisenschmuck,' or iron jewelry, became the fashion for all patriotic Prussians. Berlin became known for its finely wrought iron jewellery, which remained popular well into the mid 19th century.